Traffic bearing slab



Dec. 25, 1951 H NAGlN 2,580,185

TRAFFIC BEARING SLAB Filed May 14, 1947 2 SHEETS-SHEET l IIIII'I llll Ulli

nventor A. zlaroldv /Vayb' n Gttomegs Dec. 25, 1951 A' H, N AGIN 2,580,185

TRAFFIC BEARING SLAB Filed May 14, 194'? 2 SHEETS- SHEET 2 Snventor /Yarold [Vagin Gttvornegs Patented Dec. 25, i 1951 Harold Nagin, Pittsburgh, Pa.,\assignor to Ref liance Steel Products Company, `lVlicKeesport, Pa., a corporation of Pennsylvania v ApplicationMay 14, 1947, Serial No. 747,881

This invention is for a concrete slab for use as a vsurface forroadways, bridges and other trame bearing' structures, and is especially applicable tol constructions ofthis kind employingvmetal gratings. g j Metalgratings are commonly used'in bridge and road surfaces for both structural purposes andtraction'purposes. Generally they provide longitudinal and transverse bars welded together and the spaces between are filled with concrete, the concrete being initially flush with the grating. The surface of the slab so made presents the appearance of square orrectangular cells filled with concrete.

An objection to such slabs is thatas traine passes over the surface, the concrete wears away, leaving'cupped surfaces. If the grating is made with large cells, the cupping may become quite deep, and if the cells are too small, the tires ride principally `on the metal and skidding is less e'fectively prevented. y

l TheV present invention provides a slab in which thefwear of the concrete is minimized, and in conjunction with grating, it enables large cells to be used without excessive cupping. The invention may in addition provide additional reinforcement to the slab. My invention contemplates the use of elements in the slab which extend vertically and provide metal columns of small section or area which are flush with the original surface of the concrete. They are so placed that they take part of the load on the road surface, and hence retard wear and prevent the cupping from becoming too deep and at the same time do not provide any such continuity of metal as to cause the wheels to track and tend to retard rather than increase skidding.

My invention may be readily understood by reference to the accompanying drawings in which:

Fig. 1 is a plan view of a grating, partly filled with concrete and partly unfilled;

Fig. 2 is a transverse section through one form of slab embodying my invention;

Fig. 3 is a longitudinal section;

Fig. 4 is a plan view of another form of slab; and

Fig. 5 is a longitudinal section through another form of slab.

Referring first to Figs. 1 to 3 of the drawing, a slab is made up from a conventional form of grating which, for example, has longitudinally extending parallel bearer bars 2 with cross bars 3 connecting the same, the bars 2 being the full 3 Claims.

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depth of the grating while the bars 3 pass through the webs of the sections 2 and have their top edges ilush with the tops of the sections 2. There are transverse load distributing bars-in the lower part of the structure, these being designated 4. h

The square areas dened by the intersecting bars 2 and 3 are designated 5, andthe concrete 6 is filled into the grating and is initially flush with the tops of the members 2 and 3.

According to the present invention one' or more upright rods l are placed in each cell, lpreferably at the center. This may conveniently be done by `welding the short vertical sections of rod l to a horizontal bar 8 whichis then lightly welded into the grating before the concreteis poured. Preferably the bar 8 and the rods 'l are so set as tobring one of the upright bars l to about the centerlof each cell.' The tops of the bars 'i are Vflush withthe top of the grating.

Thevconcrete is poured intothe structure in .the usual manner. The rods might be short lengths, but preferably they' extend through substantially-the full thickness of the slab andthereby provide vertical or stirrup type reinforcements; f

It will be seen that while the'grating 'provides all of the usual advantages in the traic bearing slab, the cells may be relatively large and yet the pins or uprights I will prevent the tires from sinking too deeply into the concrete or, in other words, the pins limit the cupping action of the tires in hollowing out the concrete. At the same time the Weight of the slab and the labor cost is much less than it would be if relatively smaller cells were provided. In addition, while the posts or pins limit the wear, they do not objectionably increase the metal surface, and being discontinuous, they retard skidding, whereas an increase in the number of bearing bars and transverse bars, resulting in smaller cells, would substantially increase the cost, the weight, the labor and the continuity of the metal load bearing surfaces. Therods 1 are of relatively small cross section, being of the order of perhaps a 3A" round.

In Fig. 4 I have shown a concrete slab IU einploying no grating, but armored only with the vertical rods Il which are attached to a mesh reinforcing structure I2. Here again the rods may extend substantially through the slab, or only part way through. They are, of course, closer together where they provide the only protection. While they are shown in rows, obviously they may be staggered. The only necessity is that they be sufciently close and numerous to avoid excessive cupping of the concrete as for example from three to four inches on centers.

In Fig. 5 the slab is armored by the use of individually positioned elements I5 having an upright post portion I5a, and a horizontal thrust distributing arm portion I5b. These may be used with the grating in lieu of the arrangement shown in Fig. 1, and with or Without being attached to any frame or reinforcement.

All forms of the invention provide wear re'- sisting surfaces in a concrete slab of small exposed area capable of providing the total protection tothe wearing of the concrete or important ll-ing said spaces, said bars. and material hav`l ing yupper surfaces flush with each. other to provide a. traicbearing surface, and means for minimizing cuppingl ofthe traffic bearing material in., said spaces due toV traiic passing Vthereover comprisinga metal post arranged. vertically Y in eachw of said spaces, each of said posts having a. surface at its upper end spaced from said'reinforcing bars and iiush with and forming part of said traffic bearing surface.

2; In a traflic bearing slab, a grating structure comprising. intersecting metal reinforcing` bars arrangedto provide substantially rectangular spaces therebetween, a traiiic' bearing. material filling said spaces,4 said bars and material having upper surfaces flush with each other to provide a traic bearing surface, and means for minimizing cupping ofthe `traflc bearing' material in said spaces dueV to' tram'cfpassing" thereovercomprising a'metal reinforcing element embedded in the material filling each of saidspaces 4 and providing a surface spaced from said intersecting bars and is flush with and forms part of said traiic bearing surface, the provision of said reinforcing element surfaces enabling a wider spacing of said intersecting bars without noticeable cupping than otherwise possible.

3. In a reinforced concrete slab, a grating structure comprising intersecting metal bars positi'oned edgewise and de'ning cell areas therebetween, each of said areas having a lling of concrete therein to a level flush with the upper edges of, said bars, the edges of said bars and said'concrete cooperating to form a traihc bearingsurfaceN said bars being spaced from each other a. distance such that movement of rubberti-re'cfvehicles over the surface of the concrete therebetween would otherwise be effective to cause a'n objectionable cupping action by wearaway the concrete in said cell areas to a level below the upper edges jof the bars, and means for preventing said cupping action` consisting of afmetal reinforcing element embedded 4substantially centrallyvof each of said cell'areas. and extending vertically downwardly from said'bearing surface, the upper ends of' said elements being flush with and forming, part of said bearihgf'surface.

NGIN.

REFERENCES' CITED The following referencesare.A Aof record in the file ofthis patent:

Number Name Date 72,352 Wright Dee.' 17, 1867 174,753? McDonald Mar. 14', 1878 1,347,855 Henry July 2'?, 1920 1,645,538 MacDonald Oct.' 18, 1927 2,062,944 Sloan Dec.V I, 1936 2,187,500 Laubscher Jan. I6, 1940 2,190,214 Nagin Feb. 13, 1940 2,190,215 Nagin` Feb. 13,1940 

